Robustness is complicated, I would check if the BOM parts have a life expectancy (e.g. electrolytic capacitors are normally 3k to 10k). If there are ceramic capacitors, which may thermal shock, then did they reflow them properly and do they show signs of rework with a soldering iron. Finally, if my experience with RoHS solder is an indicator (e.g. tin pest and tin whiskers) then maybe robustness is meaningless since the thing will stop working and go in the trash in a few years.